Question

The number of moles in $19.86g$ of $Pb{(N{O_3})_2}$ (Molecular weight= $331.2{g_{}}mo{l^{ - 1}}$) equals:
$(a)0.06$ Moles
$(b)6.023$ Moles
$(c)0.6$ Moles
$(d)0.12$ Moles

Answer 1

A mole is a unit of measurement for the amount of compounds in a given quantity. It has the same number of fundamental units as the mass of the substance. A mole is a number equal to the $6.022 \times {10^{23}}$ which is known as the Avogadro number. We can calculate the number of moles by dividing the supplied substance's weight by its molecular mass.

Complete answer: The mole is a unit of measurement for the quantity of chemicals present in a sample; one mole of any substance is equal to the Avogadro number. Thus, $6.023 \times {10^{23}}$ of atoms, molecules or particles are one mole of atoms, molecules or particles. To calculate the Number of moles of a compound we can use the formula:
$n = \dfrac{m}{M}$, where ’n’ is the number of moles, ‘m’ is the given mass and ‘M’ is the molecular mass of the compound.
In the question, the Molecular mass (M) = $331.2{g_{}}mo{l^{ - 1}}$
Given mass of the compound (m) = $19.86g$
Therefore, the number of moles (n) = $\dfrac{{19.86g}}{{331.2{g_{}}mo{l^{ - 1}}}}$
$n = 0.06mol$
Hence, the correct answer is option (a).

Note:
In chemistry, the mole unit is extremely significant and useful. It is the foundation of stoichiometry, and it is the most accurate way of representing the amounts of reactants and products consumed and created during a chemical reaction. All chemical reactions can be written as a mole reaction.